Influence of the electrical stimulation on cochlear morphology and cell survival in the presence and absence of oto- and neuroprotective agents: in vitro study of novel strategies for the protection of residual hearing in patients with electric acoustic i

一些高频听力严重丧失的病人，低频听力却很好。为了保护残障患者的残余听力，提出了一种新的方法，即电声刺激（EAS）。然而，电刺激可能对内耳和残余听力造成的损害，迄今尚未得到充分的研究。这对于电刺激和声刺激之间的过渡区域尤其重要。我们之前的研究表明，双极脉冲，也用于听觉神经的电刺激，肯定会损伤毛细胞和螺旋神经节细胞，可能导致听神经变性。在本项目中，将定义保护性增产参数，以尽量减少生理完整区域的损害。通过使用各种神经和耳保护物质，我们将尝试抵消电刺激可能产生的不良影响。保护物质的有效性将被单独研究，并与电刺激结合使用各种体外系统，如分离螺旋神经节细胞培养或与螺旋神经节相连的Corti器官的器官型培养。在后者中，听觉毛细胞、支持细胞以及传入和传出轴突和螺旋神经节神经元的原始三维结构将被检查。在复杂的耳蜗结构中，单个细胞类型可能有不同的反应，这只能通过基于单个细胞的分析来检测。因此，我们的目的是对电刺激后从耳蜗中分离出来的单个细胞进行特异性分析。将研究电刺激单独和与神经保护物质联合使用对细胞（存活和神经突生长）、亚细胞（负责保护或凋亡的细胞内蛋白质或酶的激活）和基因表达水平（促或抗凋亡基因的调节）的影响。我们将特别关注毛细胞和螺旋神经节细胞之间的突触连接，因为已知的内毛细胞突触减少（50%）是听觉细胞丧失过程中的一个事件。拟议的项目应为随后申请的体内项目提供基础。在未来的项目中，将使用优化的刺激参数和选择的保护物质，以便在未来开发新的方法来可持续地保护提供EAS的患者的残余听力。

Some patients with a severe hearing loss in the high frequencies can hear well in the low frequencies. To preserve their residual hearing, a novel method, i.e., electric acoustic stimulation (EAS), was developed. The damage, however, which could be possibly inflicted to the inner ear and hence to the residual hearing by electrical stimulation, has so far not been adequately studied. This is particularly important for the transition area between the electrical and acoustical stimulation. Our previous studies demonstrated that bipolar pulses, which are also used during electrical stimulation of the auditory nerve, can certainly damage hair cells and spiral ganglion cells, possibly causing degeneration of the auditory nerve. In the present project, protective stimulation parameters will be defined to minimize the damage physiologically intact areas. Through the use of various neuro- and otoprotective substances, we will attempt to counteract possible adverse effects of electrical stimulation. Protective substances will be studied for their effectiveness alone and in combination with electrical stimulation using various in vitro systems such as dissociated spiral ganglion cell culture or organotypic cultures of the organ of Corti connected to the spiral ganglion. In the latter, auditory hair cells, supporting cells and the afferent and efferent axons and the spiral ganglion neurons in their original 3 -dimensional structure will be examined. Within the complex cochlear structures, individual cell types may react differently, which can only be detected at a single cell-based analysis. Thus, our aim is to perform specific analysis of individual cells, isolated from the cochlea after electrical stimulation. The influence of electrical stimulation alone and in combination with oto- and neuroprotective substances will be studied on cellular (survival and neurite outgrowth), subcellular (activation of intracellular proteins or enzymes that are responsible for protection or apoptosis) and gene expression levels (regulation of pro or anti-apoptotic genes). A particular attention will be paid to the synaptic connections between hair cells and spiral ganglion cells, because of already known synaptic reduction (50 %) described for the inner hair cells as an event proceeding auditory cell loss. Proposed project should generate the ground for the subsequent in vivo project that will then be applied for. In this future project, optimized stimulation parameters and selected protective substances will be used, so that in the future, new approaches can be developed to sustainably preserve the residual hearing in patients supplied with EAS.